Repairs: plumbing and heating

'Traditional' boilers

The Building Regulations no longer permit the installation of 'traditional' boilers, but there are plenty still in existence and you will encounter them in alteration and refurbishment projects. They are legal for continued use.

They tend to be rather less efficient and with a greater NOx emission on combustion.

Although it may appear to be cheaper to repair than face replacement with one of the high-efficiency boiler options described below, this should only be considered where finances are extremely tight. Even then, there is the question of availability of parts and the ongoing need for repairs. (An old boiler is likely to be one of the main issues highlighted in the report that accompanies the Energy Performance Certificate.)

If the client has limited funds or if there are a large number of boilers due for replacement within an estate/portfolio, check for any grants available at the Energy Saving Trust.

Gas condensing boilers

A gas condensing boiler is a high-efficiency system that uses an additional heat exchanger element to remove heat energy from the exhaust gas from the boiler to provide additional heat to the system.

The boiler gets its name because the water vapour produced in the combustion process condenses back into liquid (adding to the heating output). This water is removed by means of an overflow type pipe, because it cannot be recirculated in the system (it tends to be slightly acid).

The boiler is a very efficient system – even more so when operating at maximum efficiency. Take care to specify the correct size of boiler for the property. For example, there is no need to install a very large boiler in a comparatively small property, because it would be unlikely to reach peak efficiency.

The boiler costs rather more than a 'traditional' gas boiler, but the improved performance and lower fuel usage over the lifetime of the unit should defray some of the capital cost.

Combination boilers

Unlike a traditional system, the combination boiler does not heat water for subsequent storage in a hot cylinder in the airing cupboard; and there is no need for a cold-water tank or mains water domestic supply tank in the roof space.

A combi-boiler runs off mains water pressure, and a special pressure cylinder is used to take up water expansion. For this type of boiler to generate hot water, the water is drawn through the system comparatively slowly, and the flow rate is therefore rather low when compared with a traditional pumped or gravity system.

This can sometimes lead to complaints from homeowners who do not fully appreciate how the system operates, especially if they have been used to the more traditional system.

Careful selection is therefore required to optimise the flow rate for the boiler. Discuss this with the installer beforehand – preferably before specifying, so that some accurate idea of cost and performance can be assessed.

When specifying boilers of all types, you can check the government-backed 'boiler efficiency database' known as SEDBUK. This rates a wide range of boilers and is updated monthly.

Moving on

Other more efficient energy conservation systems may be available.

Biomass boilers rely on heat generated by breaking down organic matter (which might range from anything on a farm manure heap to a more refined boiler system). They can prove extremely effective – although finding the fuel source, location to store it and so on means this type of heat supply is likely to be limited to rural locations or very specific easily-serviced positions. (They require delivery of significant amounts of fuel, making inner city locations less suitable, and 'fuel miles' need to be factored into the equation.) They have proved successful for local authority district heating systems.

An alternative to the biomass boiler is the micro-combined heat and power unit (micro-CHP). This is essentially a boiler that generates electricity as well as heat. Domestic-scale systems (which can run on either biomass or conventional fuel) are only just entering the marketplace, and are therefore currently considered 'experimental'.

Increasingly attractive are ground-source heat pumps. These rely on the temperature differential between the upper and lower strata of soil around a property. Systems vary greatly depending on soil types, etc. Some need to be buried at about 3m, others at 8m. There are also systems that rely on a series of pipes set out as a network about 0.5m or 1m below the surface soil.

The heat exchanger system may have high initial costs but very limited costs thereafter (essentially, servicing and gas pressure checking of the heat exchanger) apart from the electric pump used to circulate the hot water to radiators or domestic hot water system. This system operates with a compressor, so an electricity supply is still required.

Conceivably ground-source heat pumps will be the heating system for the future, but prices need to become more realistic. This type of plant is not always suited to high density developments because the pipe grids can affect each other – in a terraced house setting, for example.

The ideal situation is to achieve a building where the fabric is so energy efficient that it can be heated by the equivalent energy from a conventional light bulb. There are then no moving parts to service, a much better built-in lifecycle cost and little subsequent energy expenditure. This is reflected in the highest level (level 6) of the Code for Sustainable Homes, which is of particular relevance to social housing projects.

Hopefully, future buildings will be highly efficient structures with no real need to heat them mechanically. Mass-based materials (brick or concrete?) may assist with balancing of the summer (cooling effect of the mass = no need for air-conditioning) with the heat retention and radiator effect of the mass material.

Plumbing materials

Vitreous ceramic is the main choice for plumbing fittings (WCs and wash basins), and offers a number of advantages including comparative cheapness and ease of cleaning.

Plastic, copper vitreous coated metal pipes and compression fittings are all used for pipework.

Be careful in the selection of the product, however, cheapest is not always best!

Modern materials offer the advantage of speed of fitting, but are not always readily compatible with refurbishment of existing properties. It may be preferable to have only one style of fitting within a building, to assist future maintenance. So there is a trade-off when considering new additions/alterations to an existing system.

Oil storage and bund wall/twin wall 'bunded' tanks

Pollution Prevention Guidelines issued by the Environment Agency provides simple advice for the prevention of pollution.

Bunding – placing some form of containment around storage tanks – is mandatory, but frequently omitted, and a significant liability could accrue should a leak occur.